[Python-ideas] Adding a new function "zip_flat" to itertools (Re: Rewriting the "roundrobin" recipe in the itertools documentation)

Steven D'Aprano steve at pearwood.info
Mon Nov 20 16:57:57 EST 2017

On Mon, Nov 20, 2017 at 12:15:50PM -0500, Terry Reedy wrote:

> >Your version truncates the results to A B C instead of A B C D E as the
> >itertools recipe gives.
> This is due to an off-by-1 error which I corrected 3 hours later in a 
> follow-up post, repeated below.

Ah, I missed that, thanks.

> > def roundrobin(*iterables):
> >      "roundrobin('ABC', 'D', 'EF') --> A D E B F C"
> >      nexts = cycle(iter(it).__next__ for it in iterables)
> >      for reduced_len in reversed(range(1, len(iterables))):
> Make that 0 rather than 1 for start value.

Is there a reason for calling reversed() instead of reversing the order 
of range in the first place?

range(len(iterables)-1, -1, -1)


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